Murat Özeren

Histopathological evaluation of melatonin as a protective agent in heart injury induced by radiation in a rat model.

INTRODUCTION Melatonin is a hormone which is known to be a powerful cardioprotective agent due to its free radical-scavenging properties. This study was carried out to evaluate whether melatonin administration prior to irradiation would have a protective effect on cardiac histopathological changes in an experimental rat model. METHODS Rats were divided into four groups. Single dose of 18 Gy radiation and sham radiation exposure were used in related groups. 50mg/kg dose of melatonin were injected intraperitonally 15 min prior to radiation exposure. Analyses and assessments were performed 6 months after radiation exposure. RESULTS Severe myocardial fibrosis was observed prominently in three regions: the apex, tips of papillary muscles and adjacent to the atrioventricular valves. Inflammation was found to be more in irradiated groups. Increased inflammation and fibrosis were in concordance. The number of mast cells was found to be decreased in irradiated groups. Myocyte necrosis and fibrosis were diminished with melatonin while vasculitis was prevented. CONCLUSIONS Elementary pathological lesions of radiation-induced heart disease (RIHD) are fibrosis, vascular damage, vasculitis and myocyte necrosis. Development of vasculitis was prevented by the use of melatonin. Fibrosis and necrosis were prominently decreased. Prevention of RIHD with the use of melatonin at the long term is encouraging according to the histopathological results.

Use of an ultrasonic scalpel in the open-heart reoperation of a patient with pacemaker.

Electrocautery has a potential risk of serious pacemaker dysfunction in patients with implanted pacemaker. Here we present the safe and efficient use of ultrasonic scalpel (Harmonic scalpel) for the first time in a patient with implanted pacemaker undergoing open-heart reoperation.

Consequences of PTFE membrane used for prevention of re-entry injuries in rheumatic valve disease

BACKGROUND The value of polytetrafluoroethylene (PTFE) surgical membrane as a pericardium substitute in patients who undergo reoperation for rheumatic valve disease is reported in this observational study. METHODS PTFE was used for pericardial closure in 56 rheumatic valve patients. During reoperation of seven cases, adhesions were classified as none, minimal, moderate to severe and scored in the sections of heart. Data found at reoperations were collected prospectively in all patients. RESULTS Seven of 56 patients reoperated mean period of 67.1+/-23.4 (SD) months later. No infection, complication and operative or late death attributable to the membrane were observed. There were two right ventricular, three minimal right atrial and one innominate vein lacerations during resternotomy and all of them were controlled. During histological examination, a microscopically significant foreign body reaction was found. CONCLUSION PTFE membrane produced an undesirable fibrous membrane that obscured the epicardial anatomy and hardened the dissection in patients with rheumatic heart disease.

Effects of levosimendan on myocardial ischaemia-reperfusion injury

Background and objective: Levosimendan has a cardioprotective action by inducing coronary vasodilatation and preconditioning by opening KATP channels. The aim of this study was to determine whether levosimendan enhances myocardial damage during hypothermic ischaemia and reperfusion in isolated rat hearts. Methods: Twenty‐one male Wistar rats were divided into three groups. After surgical preparation, coronary circulation was started by retrograde aortic perfusion using Krebs‐Henseleit buffer solution and lasted 15 min. After perfusion Group 1 (control; n = 7) received no further treatment. In Group 2 (non‐treated; n = 7), hearts were arrested with cold cardioplegic solution after perfusion and subjected to 60 min of hypothermic global ischaemia followed by 30 min reperfusion. In Group 3 (levosimendan treated; n = 7), levosimendan was added to the buffer solution during perfusion and the hearts were arrested with cold cardioplegic solution and subjected to 60 min of hypothermic global ischaemia followed by 30 min reperfusion. At the end of the reperfusion period, the hearts were prepared for biochemical assays and for histological analysis. Results: Tissue malondialdehyde levels were significantly lower in the levosimendan‐treated group than in the non‐treated group (P = 0.019). The tissue Na+‐K+ ATPase activity was significantly decreased in the non‐treated group than in the levosimendan‐treated group (P = 0.027). Tissue myeloperoxidase (MPO) enzyme activity was significantly higher in the non‐treated group than in the levosimendan‐treated group (P = 0.004). Electron microscopic examination of the hearts showed cardiomyocytic degeneration at the myofibril, mitochondria and sarcoplasmic reticulum in both non‐treated and levosimendan‐treated groups. The severity of these findings was more extensive in the non‐treated group. Conclusions: Treatment with levosimendan provided better cardioprotection with cold cardioplegic arrest followed by global hypothermic ischaemia in isolated rat hearts.

Subclinical Injury to Forearm Nerves During Radial Harvesting: Electrophysiologic Study

Abstract  Background and Aim: There are few reports about injury to forearm nerves and its potential mechanisms during radial artery (RA) harvesting. We studied electrophysiologic changes in these nerves not sought until now. Methods: Among 152 consecutive patients who underwent coronary artery bypass surgery between February 2002 and August 2002, 20 were randomized for RA harvesting and formed the study group and 20 were randomized as control group. Neurologic examination and electrophysiologic studies were performed for sensory and motor impairment of the nerves in both groups pre‐ and postoperatively. Results: There was no change on neurologic examinations before and after surgery. Electromyography (EMG) revealed significant reduction in sensory and motor conduction amplitudes of median, ulnar, and radial nerves and motor conduction velocities of median and ulnar nerves at the level of forearm in the study group. In the control group, ulnar nerve was mostly affected. When two groups are compared, sensory and motor amplitude drops of median and radial nerves and motor velocity impairment of median nerve in the study group are significant. Ulnar nerve impairments are identical in both groups. Conclusions: Handling of tissues, minor hematoma or edema along with chest retraction best explains these impairments. Patients were asymptomatic after surgery showing that EMG is highly sensitive and is not predictive of clinical impairment.

Molecular mechanism of vasorelaxant and antiatherogenic effects of the statins in the human saphenous vein graft

In this study we aimed to investigate the vasorelaxant and antiatherogenic effects of the statins (fluvastatin and pravastatin) in the human saphenous vein grafts at the molecular level by using histopathologic, pharmacological and immunochemical techniques. The saphenous vein grafts evaluated histopathologically displayed a loss in their endothelium up to a ratio of 30% and set forth indications of functional deterioration. The pharmacological evaluations proved that the relaxation responses induced by fluvastatin and pravastatin were significantly inhibited by nitric oxide synthase inhibitor, N(G)-nitro-l-arginine, and cyclooxygenase inhibitor, indomethacin, while these responses were significantly increased by angiotensin converting enzyme inhibitors, captopril and enalapril, and rho kinase inhibitor, Y27632. The results of immunochemical studies are in accordance with the results of the pharmacological studies that the related statins increased the levels of nitric oxide, phospholipase A(2) and they decreased the levels of angiotensin II and active rho kinase. On the other hand mevalonolactone, a substrate of lipid metabolism, failed to change the effects of fluvastatin and pravastatin in the related tissue. The experimental results indicate that activation of nitric oxide synthase and phospholipase A(2)-cyclooxygenase pathway and inhibition of angiotensin converting enzyme and rho kinase may have a role on the effects of fluvastatin and pravastatin in the human saphenous vein grafts. It seems that the vasorelaxant and antiatherogenic effects of the related statins are independent of their lipid lowering mechanism.

Determination of the effects of pulmonary arterial hypertension and therapy on the cardiovascular system of rats by impedance cardiography.

Aim To evaluate the effects of bosentan, sildenafil, and combined therapy on the cardiovascular system using impedance cardiography (ICG) in rats with monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). Methods Seventy male Wistar-albino rats were randomized into five groups. A single dose of MCT was given to all rats, except to the control group. After 4 weeks, bosentan, sildenafil, and combined treatment was started and lasted for 3 weeks. The last group that developed PAH did not receive any medication. Echocardiographic evaluation was performed to determine the PAH development. Thoracic fluid content index (TFCI), stroke volume index (SI), heart rate (HR), cardiac index (CI), and myocardial contractility index (IC) were determined. All procedures were performed at the baseline and after 4 and 7 weeks. Results Echocardiographic parameters showed that the all MCT-injected rats developed PAH. There were no significant inter- and intra-group differences in TFCI, SI, and IC (P > 0.05), but at the 7th week, CI value in the sildenafil-treated PAH rats was significantly higher than in other groups and HR of PAH rats with combined therapy was significantly lower than in other groups. Conclusion PAH did not have an effect on LV function of rats, or if it did, the effect was compensated by physiological processes. Also, sildenafil treatment deteriorated the LV cardiac index.

Clinical and histopathological relationship of sildenafil and bosentan treatments in rats with monocrotaline induced pulmonary hypertension

BACKGROUND Pulmonary arterial hypertension (PAH) is a challenging disorder characterized by increasing pulmonary artery pressure, which is hard to treat. OBJECTIVE This study was aimed to investigate the effects of bosentan, sildenafil and their combination. METHODS Saline or MCT were applied to Wistar rats. By the development of PAH (4th week), MCT-given rats were treated orally with bosentan, sildenafil and combination of sildenafil and bosentan or placebo. ECHO examinations were performed. Tissues obtained from all of the rats were evaluated under an electron microscope. RESULTS Left ventricular end diastolic diameter significantly increased in sildenafil and combined groups. Sildenafil group revealed a significant decrease in RV pressure and wall thickness. Examination of lung revealed a significant amount of connective tissue formation and increase in inflammatory cells in all the groups except controls in the interalveolar septum. Examination of PA revealed an increase in connective tissue volume, hypertrophic changes and expansions in granular endoplasmic reticulum cisternaes in smooth muscle cells in active groups rather than in the controls. Unlike the controls, the examination of the RV revealed an enlargement of the sarcoplasmic reticulum cisternaes in some cells, due to the calcium increase. CONCLUSION Sildenafil and the combined therapy demonstrated to have more impact on pressure and the RV parameters in rats, with lower inflammatory findings in lung tissue (Fig. 6, Ref. 31).

Usefulness of elevated red cell distribution width for predicting systemic inflammatory response syndrome after extracorporeal circulation

Objectives: Cardiac surgical operations performed by using extracorporeal circulation (ECC) lead to a systemic inflammatory response (SIR). Sometimes SIR may turn into a severe state, the systemic inflammatory response syndrome (SIRS) that usually has a poor outcome with no specific clinical tools described for its prediction. Red cell distribution width (RDW) is a routine hematological parameter. It has been proposed as a marker of morbidity and mortality in various clinical conditions. We aimed to investigate the relationship between high RDW and SIRS which is triggered by ECC. Methods: Eleven hundred consecutive patients who underwent elective heart surgery with the use of ECC were retrospectively analyzed. A total of 19 patients fulfilled the described SIRS criteria and 20 consecutive patients were selected as the control group. RDW and other laboratory parameters, preoperative clinical status, operative data and postoperative data were compared between the SIRS and the control groups. Results: Baseline characteristics of the patient groups were similar. Significant mortality was found in the SIRS group; 18 (94.73%) patients and 2 (10%) patients in the control group (p<0.002). RDW was found to be significantly higher in the SIRS group vs the control group (15.02±2.03 vs 13.01±1.93, respectively, p<0.003). Multiple logistic regression analyses showed an association between high RDW levels and SIRS development (OR for RDW levels exceeding 13.5%; 95% confidence limits of 1.0-1.3; p<0.04). Total operation time and the need for inotropic support were also found to be significant against the SIRS group (p=0.049). Conclusion: Increased RDW was significantly associated with increased risk of SIRS after ECC. The results of this study suggest that paying attention to RDW might provide valuable clinical information for predicting SIRS development among patients who are candidates for open heart surgery, without incurring additional costs.

Endovascular treatment of recurring type A dissection after total aortic arch debranching

Standard treatment method of the aortic arch pathologies is surgical replacement which requires cardiopulmonary bypass and deep hypothermic circulatory arrest. However, this approach is associated with major operative risks. Combination of debranching and thoracic endovascular aortic arch repair (TEVAR) has emerged as an alternative treatment modality in high-risk patients. This report describes successful staged hybrid treatment of a 50-year-old male patient with recurring type A dissection. It is concluded that staged debranching and TEVAR is a feasible option and provides aortic repair without increase of risk.